alum - arc
- apparent mold hardness
- apparent porosity
- apparent resolution
- apparent throat
- appearance of flame
- applied field
- apply a wash
- applying
- applying the minor load
- apportionment
- appr(ox)
- appraisal
- appreciate
- approach angle
- approach extension table
- approach lap
- approach table
- approximate reading
- approximation method
- apron